Medical probe devices are utilized for many purposes, chief of which include catheterization, centesis, and biopsy procedures. Percutaneous placement of probes using these devices is often performed with techniques which rely on palpable or visible structures. This is neither a simple nor a risk-free procedure. For instance, proper insertion and placement of a percutaneous probe depends on correct localization of anatomical landmarks, proper positioning of the patient in relation to the care provider, and awareness of both the target's depth and angle from the point of probe insertion. Risks of unsuccessful placement of a probe can range from minor complications, such as patient anxiety and discomfort due to repetition of the procedure following incorrect initial placement, to severe complications, such as pneumothorax, arterial or venous laceration, or delay of delivery of life-saving fluids or medications in an emergency situation.
Ultrasound guided techniques and devices have been developed to aid in correct placement of percutaneous probes. Ultrasound guided techniques usually require two people, an ultrasound operator who locates the internal target and keeps an image of the target centrally located on a monitor, and a care provider who attempts to guide the probe to the target based upon the sonogram. Such techniques are very difficult perceptually. For instance, these techniques are complicated by the fact that the person targeting the tissue with the probe is not the same person as is operating the ultrasound. In addition, the generally thin, cylindrical probe is usually small and reflects very little of the ultrasound beam. Moreover, as the cylindrical probe and the ultrasound beam are not generally normal to one another, the small amount of ultrasonic energy that is reflected from the probe will reflect at an angle to the incident beam, resulting in little if any of the reflected energy being detected by the ultrasound transducer. As a result, the probe itself is difficult to visualize in the sonogram and the person placing the probe must attempt to guide the probe to the correct location using minimal visual feedback provided by the ultrasound operator physically rocking the ultrasound transducer. Rocking the transducer allows the observer to see a series of planar sonograms of the internal region, and, with training, the observer can learn to recognize subtle changes in the sonograms as the probe deflects and penetrates the surrounding tissue and pick up subtle ultrasonic shadow artifacts deep to the probe created when the probe blocks the transmission of the ultrasound beam to the tissue below.
In an attempt to relieve the difficulties of ultrasound guided probe techniques, systems have been developed including a probe guide which can be attached to an ultrasound transducer housing. Problems still exist with such devices however. For instance, the probe guide is to one side of the ultrasound transducer housing in these devices, and the probe is often inserted at a fixed angle to the plane of the ultrasound beam displayed on the sonogram, restricting the intersection of the ultrasonographic beam and the point of the probe to a very small area in space. In addition, and as with hand-guided ultrasound techniques, very little, if any, ultrasonic energy is reflected from the probe back to the transducer. In fact, due to the angle between the incident ultrasonic beam and the probe in these devices, visual cues to the location of the probe tip may be even more difficult to discern on a sonogram when using these devices. In addition, in many of these devices, the probe passes through the ultrasound beam at a fixed depth range depending on the set angle of the probe guide, and this may not correspond to the depth of the target, in which case it may not be possible to show the juncture of the target and the probe tip on the sonogram at all.
What is needed in the art is an improved device and method for utilizing ultrasound to guide a probe to a percutaneous target.
Another problem that exists when attempting to place a percutaneous probe concerns movement of the probe following correct placement. For instance, after successfully placing a probe, in many procedures it is desirable for the probe tip to remain at the target location for a period of time, for instance as a catheter wire is inserted or a biopsy taken. Often, a small movement of the hand holding the probe in place can cause the probe tip to shift away from the target, leading to complications. Thus, what is needed in the art is a device and method that can clamp a probe following placement in order to limit motion of the probe tip within the body.
Yet another on-going problem faced by medical professionals everywhere is maintenance of a sterile field during procedures. Thus, what is additionally needed in the art is the ability to maintain a sterile field while utilizing ultrasound guided probe devices and methods.